ABSTRACT
Many people suffer from hair loss and abnormal skin pigmentation, highlighting the need for simple assays to support drug discovery research. Current assays have various limitations, such as being in vitro only, not sensitive enough, or unquantifiable. We took advantage of the bilateral symmetry and large size of mouse whisker follicles to develop a novel in vivo assay called "whisker follicle microinjection assay". In this assay, we plucked mouse whiskers and then injected molecules directly into one side of the whisker follicles using microneedles that were a similar size to the whiskers, and we injected solvent on the other side as a control. Once the whiskers grew out again, we quantitatively measured their length and color intensity to evaluate the effects of the molecules on hair growth and coloring. Several chemicals and proteins were used to test this assay. The chemicals minoxidil and ruxolitinib, as well as the protein RSPO1, promoted hair growth. The effect of the clinical drug minoxidil could be detected at a concentration as low as 0.001%. The chemical deoxyarbutin inhibited melanin production. The protein Nbl1 was identified as a novel hair-growth inhibitor. In conclusion, we successfully established a sensitive and quantitative in vivo assay to evaluate the effects of chemicals and proteins on hair growth and coloring and identified a novel regulator by using this assay. This whisker follicle microinjection assay will be useful when investigating protein functions and when developing drugs to treat hair loss and abnormal skin pigmentation.
Subject(s)
Minoxidil , Vibrissae , Mice , Animals , Vibrissae/metabolism , Minoxidil/metabolism , Minoxidil/pharmacology , Microinjections , Hair , Alopecia/drug therapy , Alopecia/metabolismABSTRACT
The mouse Agouti gene encodes a paracrine signaling factor which promotes melanocytes to produce yellow instead of black pigment. It has been reported that Agouti mRNA is confined to the dermal papilla after birth in various mammalian species. In this study, we created and characterized a knockin mouse strain in which Cre recombinase was expressed in-frame with endogenous Agouti coding sequence. The Agouti-Cre mice were bred with reporter mice (Rosa26-tdTomato or Rosa26-ZsGreen) to trace the lineage of Agouti-expressing cells during development. In skin, the reporter was detected in some dermal fibroblasts at the embryonic stage and in all dermal fibroblasts postnatally. It was also expressed in all mesenchymal lineage cells in other organs/tissues, including eyes, tongue, muscle, intestine, adipose, prostate and testis. Interestingly, the reporter expression was excluded from epithelial cells in the above organs/tissues. In brain, the reporter was observed in the outermost meningeal fibroblasts. Our work helps to illustrate the Agouti expression pattern during development and provides a valuable mouse strain for conditional gene targeting in mesenchymal lineage cells in multiple organs.
Subject(s)
Agouti Signaling Protein , Animals , Male , Mice , Gene Targeting , Integrases/genetics , Integrases/metabolism , Mice, Transgenic , Agouti Signaling Protein/geneticsABSTRACT
A tree-ring width chronology (STD) was established using tree-ring cores of Pinus yunnanensis from two sites with different altitudes in Western Yunnan, to study the responses of radial growth to climatic and hydrological factors. The results showed that the radial growth of P. yunnanensis in Western Yunnan was mainly affected by precipitation, temperature and runoff. The radial growth of P. yunnanensis at high altitude (2413.3 m) was controlled primarily by high temperature in summer and runoff in the monsoon season. In contrast, the radial growth of P. yunnanensis at low altitude (1062.6 m) was mainly controlled by precipitation in the growing season and annual runoff. The responses of radial growth of P. yunnanensis at high altitude to temperature change was unstable due to the existence of the temperature threshold. Due to the weakening of the East Asian summer monsoon in the 1980s, the temporal stability of tree growth response at low altitude to precipitation and runoff fluctuated. The radial growth of P. yunnanensis at different altitudes in Western Yunnan was related to the Asian summer monsoon and El Niî°o-Southern Oscillation.
Subject(s)
Pinus , Altitude , China , Hydrology , TreesABSTRACT
Due to the short-term observation record of the normalized difference vegetation index (NDVI), the research on long-term NDVI changes is scarce, which limits our understanding of the impacts of NDVI changes in the context of global warming. In this study, a regional tree-ring chronology was developed based on the tree-ring samples of Pinus tabuliformis in the middle Qinling Mountains. The results showed that tree-ring width of P. tabuliformis was significantly positively correlated with May-July NDVI (r=0.624, P<0.01, n=34). The Sig-Free tree-ring width chronology was used to reconstruct May-July NDVI during the period 1825-2018, which explained 38.9% of the total NDVI variance. Results of spatial analysis showed that the reconstructed series could better represent the NDVI changes in the study area. There were six high NDVI periods and five low NDVI periods in the past 194 years. The vegetation grew best in 2006-2018, indicating vegetation cove-rage in the middle of Qinling Mountains had been improved during the warming hiatus. Low NDVI periods in the reconstruction series were consistent with drought over much of study area. Results of wavelet analysis indicated the existence of 2-4 years and 12-16 years cycles in the reconstruction series. SEA analysis showed that the reconstruction series decreased significantly in the El Nino year, while increased significantly in the first to third years after the La Nina event. The growth of P. tabuliformis was predicted to increase slightly under the SSP2-4.5, SSP3-7.0 and SSP5-8.5 scenarios.
